Crosstab query in PostgreSQL

Question

I would like the result of this query in a crosstab:

SELECT district, sex ,count(sex)
FROM table1
GROUP BY sex, district
ORDER BY district;
district | sex | count
---------+-----+-----
dis_1 | M | 2
dis_1 | F | 4
dis_1 | NI | 1
dis_2 | M | 5
dis_2 | F | 2

Like this:

district | M | F | NI
---------+---+---+---
dis_1 | 2 | 4 | 1
dis_2 | 5 | 2 | 0

I did some testing without success, as the query below:

SELECT row_name AS district,
 category_1::varchar(10) AS m,
 category_2::varchar(10) AS f,
 category_3::varchar(10) AS ni,
 category_4::int AS count
FROM crosstab('select district, sex, count(*)
 from table1 group by district, sex')
 AS ct (row_name varchar(27), 
 category_1 varchar(10), 
 category_2 varchar(10), 
 category_3 varchar(10),
 category_4 int);

Answer 1

This crosstab function produces exactly what you asked for (except for simplified data types):

SELECT *
FROM crosstab('
 SELECT district, sex, count(*)::int
 FROM table1
 GROUP BY 1,2
 ORDER BY 1,2'
 ,$$VALUES ('M'), ('F'), ('NI')$$)
AS ct (district text
 ,"M" int
 ,"F" int
 ,"NI" int);

You had a couple of errors in your attempt.
Find details and explanation in this closely related answer:
PostgreSQL Crosstab Query

Answer 2

You can use an aggregate function with a CASE expression to get the result in columns:

select district,
 sum(case when sex ='M' then 1 else 0 end) M,
 sum(case when sex ='F' then 1 else 0 end) F,
 sum(case when sex ='NI' then 1 else 0 end) NI
from table1
group by district
order by district